linux-kernel - Re: Problem about CPU stalling in hrtimer

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Message-ID: <alpine.DEB.2.11.1510241854410.4639@nanos>
Date:	Sat, 24 Oct 2015 18:58:18 +0900 (KST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Yang Yingliang <yangyingliang@...wei.com>
cc:	Ding Tianhong <dingtianhong@...wei.com>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Hanjun Guo <hanjun.guo@...aro.org>
Subject: Re: Problem about CPU stalling in hrtimer_intterrupts()

On Thu, 22 Oct 2015, Yang Yingliang wrote:

> But I found out when the cpu is stalling, basenow.tv64(7676664221321) is
> bigger than ktime_get().tv64(7336008904750) in hrtimer_interrupt() and
> the timer->_softexpires is 7336288000000. This makes it can not finish
> the while loop until ktime_get().tv64 arrives basenow.tv64.
> 
> Is it correct that basenow bigger than ktime_get() ?

You only can compare basenow and ktime_get() for the clock monotonic
base. If you are actually observing this on clock monotonic base then
base->offset of clock monotonic is not 0, which should never happen.

Thanks,

	tglx
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